This invention relates to surgical appliances and, more particularly, to systems for retracting the sternum for gaining access for cardiovascular surgery, principally coronary artery bypass grafting using the internal mammary artery.
1. Background of the Invention
Coronary artery bypass grafting (CABG) in humans was introduced nearly a half century ago. The first reported CABG using the internal mammary artery (IMA) in humans was performed in 1960. However, saphenous vein grafting became the most common CABG technique for the next two decades. By the mid 1980""s, however, it was recognized that the long-term survival rate of CABG was significantly higher when the IMA rather than the saphenous vein was used. Saphenous vein grafting supplemented by the IMA and occasionally gastroepiploic artery, inferior epigastric artery, and radial artery, has enabled complete arterial revascularization to be performed in almost all patients. Coronary artery bypass grafting is the most common procedure performed in adult cardiovascular surgery today. In the graft selection for CABG, the first choice is the left IMA and the second choice is the right IMA.
The IMA is in close proximity to the heart and therefore it is not necessary to completely remove it from the patient. The side branches are hemostatically severed, the main trunk of the vessel is occluded with a clamp, and then the IMA is severed at a point just superior to the patient""s diaphragm so that the IMA is mobilized without disconnecting it from its original blood supply. The freed end of the IMA is then anastomosed to a coronary artery, usually to the left anterior descending coronary artery, just distal to the stenosis.
The procedure for harvesting the IMA requires significant access and visibility into the underside of the upper thoracic cavity for the surgeon. The surgeon must free the IMA from the wall of the internal thoracic cavity. The side branches of the IMA must be located and transected with minimal blood loss.
The most commonly used method of access to the thoracic cavity for the mobilization of the IMA and the anastomosis of it to the left anterior descending coronary artery is a median sternotomy. For this procedure, a longitudinal incision is made through the patient""s sternum on the midline of the chest. Then a surgical retractor is used to spread and hold apart the left and right rib cages, creating an opening. Since the IMA is attached to the thoracic cavity wall, the angle of approach the surgeon must use through the opening is very difficult since the inferior rib cage tends to obstruct the manipulation of surgical devices used for the procedure.
It is also important that the retracting apparatus be easy to clean and sterilize for reuse, or that it be low cost and disposable. The retractor must be stable during the surgical procedure, to maintain the lifting/retracting orientation desired by the surgeon, and to be as atraumatic as practical to the surgical patient. It is also highly desirable that the retractor allow for only the amount of retraction required by the surgeon to further minimize patient trauma.
2. Discussion of the Prior Art
Fakhrai, U.S. Pat. No. 4,622,955, describes a surgical retractor to be mainly used for dissection of the internal mammary artery. It is fixed to the side of the operating bed by a clamp which can be moved over the rail for the desired place. It""s pole will be at either side that internal mammary artery is intended to be dissected, side arm of the pole will be over the patient and holding the crank mechanism to which retractor hooks are attached by a cable. By placing the hooks of the retractor at the edge of the sternum, after being split at the middle, and cranking the handle the sternum is retracted. The crank portion of the retractor, which is adjustable over the side arm of the pole, will pull and elevate the side of the chest and hold it in position for the time that is needed for the dissection of the internal mammary artery.
Other crank operated retractors are described by Rullo, et. al., in U.S. Pat. Nos. 5,964,699; 5,984,866; 6,083,153; 6,090,042; and 6,228,026. Rullo, et al., U.S. Pat. 6,083,153, describes, for example, a xiphoid retraction system that includes a set of rakes for use as surgical retractors in a surgical procedure in which the set of rakes includes a progressively longer body-supporting base portion and a C-shape surgical retraction device adapted for use in a mid-cab surgical procedure. A set of rib rakes are provided for retraction of the patient""s ribs and thoracic region in a mid-cab procedure, in which each retractor rake has a progressively larger body-supporting portion for use in, for example, the dissection of the internal mammary artery during its harvest for use in a coronary bypass procedure.
A similar concept, for use in breast implant surgery and using a pulley, is described by Forrest, et. al., in U.S. Pat. Nos. 5,065,739 and 5,109,831.
The method of using retraction apparatus depends, of course, on the particular surgical procedure with which it is used and the preference of the surgeon rather than upon the particular apparatus per se. In a general sense, however, a common method has been used for many years and is described here simply as an example of methods that can be used. An incision is made in a patient extending from near the patient""s xiphoid process to near the patient""s manubrium and a retractor device of some sort is attached to the patient""s sternum, typically with one blade or rake near an attachment point of the patient""s xiphoid process and a second blade near the manubrium. A retracting force is applied to the retractor to enlarge the surgical cavity.
While prior art apparatus using crank devices or pulleys perform the necessary retracting function, they are quite complex mechanically, difficult to assemble and use, and prone to malfunction during surgery. One common problem with the prior art devices is use of a single retractable cable attached to a horizontal support which secures the retractor rakes. This structure causes pivoting of the horizontal support about the point of cable attachment and makes independent actuation of the retractor rakes to provide precise amounts of retraction difficult or impossible. The advantages of prior art crank retractor systems is retained in the present invention but the present device is much easier to assemble and to use and is more reliable in use. In addition, more stable, precise retraction is obtained because the degree and direction of retraction is not dependent upon cables or chains which tend swing about. Moreover, the present invention enables independent actuation of retractor blades or rakes, which facilitates minimal patient trauma.
Geister Medizintechnik GmbH produces the xe2x80x9cKobinia IMAxe2x80x9d retractor that uses an axially rotated knob which engages a coarse screw thread on a retractor shaft to actuate the retractor. The Omni-Tract Surgical xe2x80x9cPittman IMAxe2x80x9d has a similar design. Rotating the knob is slow and cumbersome and provides minimal mechanical advantages to the user. The threads of the retractor shaft also provide a crevase that complicates cleaning and sterilization.
The retractor system described herein provides the advantages described and solves some of the above problems. A surgical access of variable size is provided using an easily adjustable but very stable set of mechanisms. The retractor is easily sterilized such that it can be reused with complete safety. The retracting mechanism is largely out of the surgical field and thus provides maximum access to the surgical sites.
A first aspect of the present invention is a surgical retractor system for retracting tissue of a patient. The retractor system includes a horizontal support and first and second retractors are attached to the support. The first and second retractors are laterally spaced along the support to enable independent retraction of a patient""s tissue at select points spaced lengthwise of the patient. A gimbaled attachment is provided between at least one of the first and second retractors facilitating and the horizontal support. The gimbaled attachment preferably facilitates lengthwise movement of the retractor along the horizontal support. Preferably the horizontal support consists of a bar having a diameter and a gimbaled attachment consists of a support passage axially receiving the bar defined in the retractor. The support passage includes a curved surface configured to engage the bar diameter tangentially to provide selective lengthwise and gimbaled movement of the retractor relative to the horizontal support. The support passage preferably includes a major dimension substantially perpendicular to the support bar and a minor dimension perpendicular to the major dimension. The minor dimension is slightly longer than the diameter of the bar and the curved surface extends into the minor dimension to provide an effective diameter of the minor dimension that is less than the diameter of the bar.
The retractor preferably includes a retractor shaft having a distal and a proximal end with a tissue engaging blade on-the distal end. A ratchet receives the retractor shaft between the distal and proximal ends to enable selective retraction of the patient""s tissue engaged by the blade along a first direction. The ratchet preferably includes a frame and a release trigger defining a first hole receiving the retractor shaft. The release trigger is pivotally attached to the frame and biased to engage the perimeter of the first hole with the retractor shaft to prevent movement of the retractor shaft relative to the frame in a second direction opposite the first direction. The ratchet may further include an actuator defining a second hole receiving the retractor shaft spaced lengthwise of the retractor shaft from the release trigger. The actuator is operatively associated with the frame to engage the perimeter of the second hole with the retractor shaft upon movement of the actuator in an actuation direction relative to the frame to move the retractor shaft in the first direction. The actuator preferably consists of an actuator plate defined the second hole and an actuator handle pivotally attached to the frame and operatively associated with the actuator plate to engage the perimeter of the second hole with the shaft upon pivoting of the actuator handle in the actuation direction.
A second aspect of the present invention is a surgical retractor consisting of a retractor shaft having a distal and proximal end with a tissue engaging blade on the distal end and a ratchet which receives the retractor shaft between the distal and proximal ends to enable selective retraction of patient tissue engaged by the blade along the first direction. The ratchet preferably includes a gimbaled attachment to the support member. The support member is preferably a bar having a diameter and the gimbaled attachment includes a support passage defined in the ratchet for axially receiving the bar. The support passage includes a curved surface configured to engage the bar diameter tangentially to provide selective gimbaled movement of the ratchet relative to the bar. The ratchet preferably consists of a frame and a release trigger defining a first hole receiving the retractor shaft. The release trigger is pivotally attached to the frame and biased to engage the perimeter of the first hole with the retractor shaft to prevent the retractor shaft from moving relative to the frame in a direction opposite the first direction. An actuator defining a second hole receiving the retractor shaft is preferably operatively associated with the frame to engage the perimeter of the second hole with the retractor upon movement of the retractor in an actuation direction relative to the frame to move the retractor shaft in the first direction. The retractor may consist of an actuator plate defining the second hole and an actuator handle pivotally attached to the frame and operatively associated with the actuator plate to engage the perimeter of the second hole with the shaft upon pivoting of the actuator handle in the actuation direction.
The retractor system of the present invention is easy to set up and can be set up quickly. It can be attached to the operating room table and completely set up in less than a minute. The subject retractor system utilizes low profile retractor blades which minimize obstruction of the surgeons view and access to the surgical field. Retraction is accomplished quickly and simply with virtually infinite variability using a system that gently and evenly elevates the sternum. The retractor system has particular utility for IMA dissection that facilitates grafting of an internal mammary artery to an anterior descending coronary artery.